A display device refers to a device with a display panel capable of displaying an image based on a image signal/video data of various formats or a broadcast signal, and is materialized by a TV, a monitor, etc. Such a display panel has various types such as a liquid crystal display panel, a plasma display panel, etc. according to its characteristics and is applied to a variety of display devices.
The display devices are different in brightness and chromaticity of an image displayed thereon due to their electric, physical and optical features. Therefore, a image signal output from one source is displayed with slightly different colors on the different display devices. For example, although the same broadcasting program is given to the display devices through a sky wave or a satellite, the color of the broadcasting program is varied depending on what display devices the broadcasting program will be displayed on.
Further, if light outputs of pixels in a display device having a high resolution are not uniform, problems of image blurring and the like may arise.
To solve these problems, calibration is carried out for making the light output of the display panel uniform. During the calibration, a displayed image is sensed and analyzed by a color sensor to determine a calibration coefficient, the determined calibration coefficient is provided to the display device, and the display device calibrates the light outputs of the pixels based on the calibration coefficient.
In case of a high-resolution display device with a plurality of modules, each module has to be accurately calibrated for a high-resolution display because many modules of the display device are different in characteristics. To this end, the calibration has to be applied to each pixel of a screen. Each individual module has a uniform characteristic, but overall uniformity is deteriorated due to variations between the modules when the modules are connected into one.
Accordingly, there has been proposed a method of connecting all the modules to constitute the display device and then performing the calibration. However, this method has problems in that it is difficult to secure a space since a limitation in the resolution of the color sensor requires a long sensing distance and it takes too long time.